1. Preheat oven to 375 degrees F (190 degrees C).
2. Sprinkle the lemon juice and 1 tablespoon of olive oil over salmon fillets, then season them with salt and pepper.
3. Line a medium baking dish with aluminum foil (optional). Use the rest of olive oil to grease foil.
4. Arrange salmon in the prepared baking dish and bake, uncovered, for about 15 minutes, or until fish is easily flaked with a fork.
5. While the fish is baking, melt butter in a small saucepan over medium heat (leave 1/2 tablespoon of butter for later), stir in the flour.
6. When the mixture is well blended, stir in milk.
7. Add all purpose seasoning and dill weed. Reduce heat, and continue to cook and stir until thickened.
8. Remove the creamy mixture from heat, and put the rest of butter on top.
9. Pour evenly over the salmon to serve.